Method for providing attachments between a concrete part to a further part

ABSTRACT

A method for providing a connection between concrete parts. One of the concrete parts is provided with a number of encased, projecting reinforcing bars. The other concrete part is provided with a series of cavities in which said reinforcing bars are placed and are then fixed to the concrete part in question by being encased. The cavities are produced by encasing a body, which at least on the outside comprises a polysiloxane material, in the concrete. When a tensile force is applied to the body a considerable reduction in its cross section takes place, so that it is possible for the non-sticking body to be removed from the concrete in a simple way, after which the desired cavity remains.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to method for arranging a cavity in aconcrete part. A method of this type is known from Belgium patent502991. This patent describes the production of a cavity by theintroduction of an elastomeric material into a formwork. This rubberelastomeric material extends through the boundary wall of the formwork.At the location where it passes through the formwork, the rubberelastomeric material forms an acute angle, so that a larger cavity isformed as a result of the formwork wall being provided with a number ofauxiliary parts at that location. After the concrete has been poured,the rubber elastomeric material is removed and a stay or cable isarranged in the cavity formed in this way and tensioned by couplingparts which act on it from the outside.

2. Description of Related Art

GB 682320 discloses a method for providing an elongated cavity in aconcrete article for receiving reinforcement elements such as a numberof wires, which might be highly tensioned to form a pre-stressed beam orgirder.

SUMMARY OF THE INVENTION

It is an object of the present invention to make it easier to coupleconcrete parts and other parts to one another. In the prior art,concrete parts are coupled to one another by a concrete part beingprovided with projecting (threadable) reinforcing bars (dowels andplug-connection anchors) and the other concrete part is provided withcavities which match them. After they have been put together, the spacebetween the concrete bars and the cavities in the concrete part arepoured full of concrete. These cavities are produced by fitting pipesinto the formwork before the concrete is poured. After the concrete hasbeen poured out, these pipes remain behind in the formwork. This firstlyentails considerable costs, since the pipes have to be considered lost,meaning considerable outlay. Secondly, bonding takes place between theconcrete and the pipes and between the pipes and the reinforcing bar.

The object of the present invention is to provide a method of this typewhich enables a concrete part to be secured to the surroundings.

According to one aspect of the present invention, this object isrealised in a method for securing a metal part in a concrete part,comprising the steps of providing a concrete part having a cavity whichextends from an outer wall thereof of providing a formwork, of placing abody into said formwork, the shape of which body at least partiallycorresponds to said cavity and that side of which body that adjoins theconcrete material comprising an elastomer material, the mechanicalproperties of said body being such that, when a tensile force is appliedto said body in the vicinity of said boundary surface, the diameter ofsaid body is considerably reduced, with the result that said body, afterthe concrete has been poured and at least partially set, can be removedfrom said shaped cavity, which diameter of said body can be elasticallyreduced, of pouring and at least partially setting the concrete,detaching said formwork and said body and securing said metal part insaid cavity.

The length (depth) of the cavity produced in this way is preferably atleast 20 cm.

This securing may comprise “adhesive bonding” in accordance with anadvantageous embodiment. The term adhesive bonding is understood asmeaning the use of all types of adhesive materials which provide aconnection between the metal part which has been introduced into thecavity and the concrete wall of the cavity. The wall of the cavity ispreferably profiled in order to improve adhesion. The same is true ofthe outer side of the metal part.

According to another aspect of the present invention, this object isachieved by a method for arranging a series of cavities, which extend asfar as an outer wall of a concrete part, in said concrete part,comprising the steps of providing a formwork, placing a series of bodiesinto said formwork, the mechanical properties of each body being suchthat when a tensile load is applied to said body, there is aconsiderable reduction in the diameter of the body in the vicinity ofsaid boundary surface, with the result that said body can be removedfrom said shaped cavity, which reduction in diameter of said body iselastic, each cavity comprising a blind hole which is delimited only bysaid body and the boundary wall which, in the vicinity of thebody-boundary wall contact surface, extends substantially perpendicularto the longitudinal extent of said body.

The invention also relates to a concrete part which is to be coupled toa further concrete part, comprising, at the boundary surface with saidfurther concrete part a series of cavities which extend substantiallyperpendicular to said boundary surface, the boundary wall of saidcavities comprises concrete. The invention also relates to an assemblycomprising two concrete parts secured to one another, comprising aconcrete part as described above and a further concrete part which isprovided, at the boundary surface with the concrete part, with a seriesof projecting reinforcing bars which, in the coupled state to saidconcrete part, extend into the cavities in said concrete part, the spacebetween said cavities and said reinforcing bars being filled with amaterial which bonds said reinforcing bars to said concrete body.

The reinforcing bars in the further concrete part may be encasedtherein, but it is also possible for them to be fitted into cavitieswhich have been produced in the manner described above. Cavities of thistype may have a smooth wall, but are preferably profiled to some degreein order to improve bonding to a reinforcing bar or the like when, forexample, adhesive is used. However, it is also possible for a cavity ofthis type to be provided with a screw thread, so that the reinforcingbar or threaded part can be screwed into the corresponding cavity.

The invention proposes positioning a body in the formwork and removingthe body again after the (partial) setting of the concrete. Unlike inknown structures, at least the outer side of this body is made from anelastomer material. The properties of the body are such that when atensile force is applied thereto, during removal, the cross section(diameter) of said body becomes considerably smaller. This reduction indiameter is elastic, i.e. after the tensile force on said body has beeneliminated during removal from the concrete, the body returns to itsoriginal form and can be reused, i.e. a cavity which corresponds to theexterior of the body can be produced in the concrete without significantdamage to the external surface of the body. A body of this type can beused a large number of times. The cost of producing cavities drops as aresult, while moreover the abovementioned method is particularly easy toemploy. The body is easy to remove by hand.

One example of an elastomer material which has the properties describedabove is a polysiloxane material. This material undergoes considerableconstriction when a tensile force is applied, and moreover has notendency whatsoever to stick to the concrete material, so that removalfrom the partially set concrete material is possible with even only aslight reduction in the size of the cross section.

The above-described body may be hollow or solid and in any externalperipheral form. Examples include round, oval and polygonal. In allcases, it is possible for an optionally hollow core, which consists of amaterial with a higher tensile strength than the elastomer wall of thebody, to be present adjacent to the outer part of the body which isformed from the above-described elastomer material. An embodiment ofthis type is advantageous in particular for relatively great lengths.This core can take care of the bearing function. After all, if the bodyprojects into a space unsupported over a considerable distance, as isthe case when it is positioned prior to pouring into a formwork, somestrength is required in order to prevent the body from being deformed ordeviating from the desired position.

It is also possible for a permanent part which adjoins the removablebody to be arranged in the poured concrete object, for example aconnecting pipe between the passages or the connection to anothersurface.

Another possibility is to provide a further cavity which is connected tothe cavity which is to be formed and in which the metal part is to besecured, which further cavity extends as far as a separating surface ofthe concrete part. As a result, the bonding material which has toprovide the bond between the metal part and the wall of the cavity canbe introduced.

The body may either consist entirely of an elastomer or may comprise acombination of a relatively rigid core with elastomer material arrangedaround it.

In a variant, it is possible for the core to be separable from theelastomer material. The removal of the core produces a large amountspace for the elastomer material to move back from the partial settingof the concrete. This is important in particular in the case of complexformations. According to a further variant of the invention, it ispossible to design the core to be expandable. As a result, the size ofthe core can be reduced after the concrete material has at leastpartially set and the core can readily be removed. In the vicinity ofthe periphery, the body may be provided with a reinforcement, such as acoil. The above-described mechanism wherein the diameter is producedduring the application of force to the body can be used not only forremoval of the body from set concrete but also to provide a seal betweenthe body and the formwork.

Another option is to place the end face of the body against theformwork. By arranging a threaded bore in the end face (the core) orproviding the latter with a projecting threaded part and producing arelatively small hole in the formwork, it is possible to fit either abolt or the threaded stud through this hole and be supported on theother side of the formwork. The core is preferably only connected to theouter casing in the vicinity of the formwork end. When a tensile forceis applied, the outer casing is gripped at the end and can easily bereduced in size. This reduction in size can in extreme circumstances beimproved still further by providing the outer casing with aconcertina-like profile on the inner side.

In all cases, it is important for the body to be designed in such amanner that it is not deformed by its own weight and/or weight of theconcrete poured onto it. This means that, starting from securing to theformwork, the body has to be sufficiently strong and/or self-supportingfor it not to be deformed or deviate from the desired position.

The method described above can be used to produce any conceivable typeof cavity in a concrete material. A number of non-limiting examples willbe given below.

It will be understood that it is possible to arrange a number ofcavities next to one another in a single step. In such a case, theformwork has to be provided with a series of bodies (which may differfrom one another) and which are then encased with concrete. These bodiescan either be removed simultaneously or removed in succession. In aparticular embodiment, a common bearing plate will be used. This bearingplate is placed against a formwork and, by providing the later with aparticular profile, can likewise provide the concrete object which is tobe formed with a particular profile, such as for example a V-shapedprofile. A V-shaped recess obtained in this way can provide stabilizingfunctions when a further part is poured onto it. There are various usesfor a successive number of cavities of this type. These cavities may beidentical and/or different.

The invention also relates to a method for connecting two concrete partsto one another, comprising the steps of arranging a projectingconnecting member, such as a reinforcing bar, in one of said concreteparts, providing said other concrete part with a cavity as describedabove, placing the concrete parts against one another, with saidprojecting member being placed into said cavity, and securing saidprojecting member in said cavity.

Therein the projecting member can be introduced into said one concretepart by producing a cavity in the manner described above and adhesivelybonding or screwing it or connecting it in some other way into saidcavity. A method of this type can be used to temporarily or permanentlysecure two or more concrete parts. Moreover, it can be used fortemporary or permanent propping-up.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail below on the basis ofexemplary embodiments illustrated in the drawing in which:

FIG. 1 diagrammatically depicts a first embodiment of the body forproducing cavities in concrete parts;

FIG. 2 shows a second embodiment of a body of this type;

FIG. 3 shows the positioning of a series of bodies in a formwork inaccordance with the invention; and

FIG. 4 shows the inventive way of putting together an assembly.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, a body for the production of cavities is denoted by 92. Itcomprises a metallic core 93 around which a rubber-like material 94 isarranged. This rubber-like material may comprise any material which isknown in the prior art, such a polysiloxane material. This material hasthe particular feature that, when a low tensile force is applied to it,it undergoes considerable stretching, resulting in a considerablereduction in the cross section of the body 92. The rubber-like materialused has a Shore A hardness of less than 40 and preferably of 20 orless. The external shape of the body 92 may be any desired form. Thatend of the body 92 which is denoted by 95 is of narrowed design. Theother end is provided with a threaded part 99.

Depending on the embodiment, the core 93 may optionally be arranged soas to be removable with respect to the rubber-like material 24.

FIG. 2 shows a variant of the structure shown in FIG. 1. The body isdenoted overall by 102 and comprises a relatively rigid core, forexample made from metallic material 103. The part made from rubber-likematerial is denoted by 104. A part having a number of spacers 106 isarranged between this piece of rubber-like material and the relativelyrigid core. The narrowed end is denoted by 105 and the threaded part isdenoted by 109.

FIG. 3 and FIG. 4 show the use of the invention for coupling a concretepart 85 to a further concrete part 86 (FIG. 4) in more detail. Thisfurther concrete part 86 is provided with preferably single solidreinforcing bars 87 which are encased in concrete in a manner which isknown from the prior art. However, according to a preferred embodiment,the method according to the invention is used to provide this part 86with reinforcing bars, so that the two parts 85, 86 are deliveredwithout reinforcement and with holes at the top. A series of, i.e. atleast three and preferably at least ten, bars of this type are arrangedin specific positions depending on the requirements set. They are to bearranged in cavities which are denoted by 88 and are produced in theconcrete part. After or before introduction, the cavities are filledwith a bonding material which forms an adhesive bond between theboundary of the cavities 88 and the reinforcing bars 87. A material ofthis type may comprise a pourable mortar or (two-component) syntheticresin or any other known bonding agent which is known from the priorart. The length of the freely projecting part of the reinforcing bars ispreferably at least 20 cm.

According to present invention, the boundary wall of the cavities 88 isformed by concrete material, unlike in the prior art, in which thecavities are produced by boundaries made from another material. Thecavities according to the invention are produced in the manner shown inFIG. 3. 89 denotes a formwork which may comprise any material that ispreferably of metallic design, so that it can be used a number of times.This formwork is provided with a number of openings 90 which can eitherbe closed off by stoppers or through which bolts 91 can extend. Thesebolts 91 extend from the outer side of the formwork toward the interiorfor fixedly securing bodies 92 and 102 with screw thread 99 and 109,respectively, in accordance with the present invention. After securingto the formwork, no further support for the bodies 92 or 102 isrequired, on account of the strength of the core, and concrete can bepoured. After at least partial setting, first of all the bolts 91 areremoved, followed by the removal of the formwork 89. Then, in the mannerdescribed above, the bodies 92 and 102 can be removed by the applicationof a tensile load to them. As has already been indicated above, theexternal rubber part, which does not stick to the concrete material,will undergo a considerable reduction in size with considerablestretching as a result of the application of a tensile load. It is alsopossible for cores 93 and 103 to be removed first, after which therubber-like material 94/104 is particularly easy to remove. In this way,it is possible to provide cavities without the use of pipes or otherauxiliary means. As a result, complicated structures withplug-connection receptacles and the like can be made considerably moreeasily.

As a result of the accurate positioning of the bodies 94, it is alsopossible to accurately fix the position of the cavities 88 with respectto the reinforcing bars. As a result, the cavities can be designed witha relatively small diameter and the narrowed region 95 serves to furthercenter the reinforcing bars. As an alternative to reinforcing bars, itis also possible to arrange nut-like structures or other structuresaround the body 92 and/or 102. After the concrete has been poured in andpartially) set, the body 92 and/or 102 can be removed, leaving behindthe nut-like structure or the like in the concrete body.

In the exemplary embodiment illustrated in FIG. 4, the reinforcing bars87 have been encased in the further concrete part 86. It should beunderstood that the technique of arranging cavities and then fixing thereinforcing bars therein described above can also be used for thefurther concrete part or concrete part which is still be to be poured.This can take place in the manner described above with the aid, forexample, of adhesive bonding. However, it is also possible for theencased bodies with an external surface made from rubber-like materialwhich are then used to be provided with an external screw thread. As aresult, the cavity in the concrete material is likewise formed with ascrew thread into which reinforcing bars of this type or otherstructural parts can be screwed and fixed in place. Structures withwalls cast onto them are also conceivable.

It will be immediately clear to the person skilled in the art from thevariants described above that the invention can be implemented in a widerange of ways. Further variants will occur to the person skilled in theart on reading the above description and such variants lie within thescope of the appended claims.

The further part provided with projecting reinforcing bars is fittedinto the openings 88. It is possible for these openings to be providedwith a bonding material in advance. It is also possible for a materialof this type to be applied subsequently. For this purpose, the openingsare lengthened by a grouting hole 83. These can be formed, for example,by fitting a curved plastic pipe opening from the body in the formworkand leaving this pipe in place in the concrete after it has beenencased. Adhesive material, such as a mortar, can be applied via thisgrouting opening 83. Of course, it is also possible for a material ofthis type to be introduced via opening 88.

As an alternative to a single further part from which reinforcing barsextend, it is possible of this further part simply to be provided withcontinuous cavities. After the part with blind cavities and the partwith continuous cavities have been placed onto one another, with thesecavities aligned, it is possible, for example, to place reinforcing barsin the cavity and for adhesive bonding material to be introduced (ifappropriate in advance). This makes it possible to avoid expensivethrough-coupling systems.

The further concrete part described above may also comprise any otherconceivable part and it is also possible for the cavity and the partwhich is to be introduced to be used or arranged in any desiredposition. In this context, consideration can be given toscaffolding/rail-securing means/exterior-panel anchoring means,anchoring means which interrupt thermal bridges and the like.

It is also possible for a holder made from plastic or some other type ofmaterial to be secured to the formwork, in which part of the body can bereceived, so that the body can be put in place without bolt connectionsthrough the formwork, or in special cases with magnets for example.Moreover, it is also possible for the body to be positioned at a definedangle in the formwork.

As an alternative to the formwork wall 98 shown in FIG. 1, it is alsopossible to provide a plate (or holder) on which the bodies 92 and 102are arranged as a series. These bodies may then be identical ordifferent in shape and may be at identical or different distances fromone another. It is possible for a plate (or holder) of this type to beprovided with a profile which, of course, will be transferred to theconcrete which is to be poured. A plate of this type can be secured tothe formwork in any desired way or may form part of the formwork.

If openings are being produced on the top side of a concrete body, i.e.at a location where no formwork is required, the bodies described abovecan be designed to float in the concrete with the aid of “floatingstructures”.

1. A method for coupling concrete parts, comprising the steps of: providing a formwork, said formwork including an inner side; placing a plurality of bodies against said inner side of said formwork, each of said bodies having a shape and including an elastomer material, each body being configured such that when a tensile force is applied to said body, a diameter of said body is reduced; pouring and at least partially setting concrete material about said formwork and said bodies so as to form a first concrete part having a plurality of cavities formed therein, each cavity having a shape at least partially corresponding to the shape of one of said bodies and extending from an outer wall of said first concrete part, wherein the elastomer material of each of said bodies adjoins concrete material and then each of said bodies can be removed from said cavities by applying a tensile force to each of said bodies at the outer wall of said first concrete part; detaching said formwork and said bodies from said first concrete part; providing metal reinforcing bars which are receivable within the cavities in said first concrete part; and securing said reinforcing bars in said cavities, said securing step including filling a space within each cavity between said metal reinforcing bars and said first concrete part with a material which bonds to said reinforcing bars and to said first concrete part, said metal reinforcing bars being encased in the concrete of a second concrete part.
 2. The method as claimed in claim 1, wherein at least one of said plurality of bodies is externally provided with a profiling.
 3. The method as claimed in claim 1, wherein said securing step comprises the step of screwing at least one of said metal reinforcing bars into a screw thread arranged in at least one of said cavities.
 4. The method as claimed in claim 3, wherein said screw thread comprises an encased threaded part.
 5. The method as claimed in claim 1, wherein at least one of said bodies is secured to the inner side of the formwork.
 6. The method as claimed in claim 1, wherein said first concrete part is poured in a factory remote from its final destination.
 7. The method as claimed in claim 1, wherein said metal reinforcing bars comprise reinforcing steel.
 8. The method as claimed in claim 1, wherein said elastomer material comprises a polysiloxane material.
 9. The method as claimed in claim 1, wherein at least one of said bodies comprises a core made from a material with a higher tensile strength than a wall of the body and is provided with a supporting surface and is self-supporting.
 10. The method as claimed in claim 1, wherein at least one of said bodies is provided, at an end thereof, with a securing element for securing the body to said formwork.
 11. The method as claimed in claim 1, wherein at least one of said bodies is provided with a series of projections which, when fitted into said formwork, extend at a distance from an end of one of said cavities opening out at said outer wall of said first concrete part.
 12. The method as claimed in claim 11, wherein said projections comprise an external screw thread.
 13. The method as claimed in claim 1, in which at least one of said bodies is provided with a receiving means for a part which is to be encased, and after the concrete material has set, said part which is to be encased remains behind in the set concrete material when said body is removed.
 14. The method as claimed in claim 1, wherein at least one of said bodies comprises a core with the elastomer material arranged around the core, and wherein the step of detaching said body from said first concrete part comprises firstly removing the core, followed by removing the elastomer material. 